Like most 16-year-olds, Brooke Greenberg enjoys shopping and listening to rock music.

But unlike other girls her age who are learning to drive and going to the prom, Brooke still wears diapers, travels in a stroller and can’t walk or talk. Like a toddler, Brooke is 2-and-a-half feet tall and weighs only 16 pounds.

Doctors aren’t sure how or why, but Brooke, who lives in Baltimore, Md., developed a mutation of the gene that controls aging and development.

Dr. Richard Walker, a biomedical researcher and editor-in-chief of Clinical Interventions in Aging, discovered Brooke’s mutated gene. He has been studying her case since 2006.

“Brooke is a unique individual because she has a mutation in the developmental gene that prevents her from aging, and she’s in the developmental phase,” Walker said. “There’s no hope for her, but what she brings to science is information on how we may be able to delay aging.”

Brooke, one of four children, is definitely a “Daddy’s girl.” Her father spares no expense for his daughter. Like her sisters, Brooke had a Bat Mitzvah — the Jewish rite of passage into adulthood — when she turned 13. And he buys her the best strollers and baby swings.

“That’s what she really loves,” said Caitlin Greenberg, 19, pointing to the swing, as Brooke propelled herself back and forth, a smile forming on her small face.

Caitlin, a sophomore at Towson University, and her other sisters, Emily, 22, and Carly, 13, are of normal size and development. They still interact with their “little” sister as if “she’s just one of the gals,” Caitlin said.

But it’s a difficult life for the Greenbergs. The state of Maryland has provided two nurses to help care for Brooke 16 hours a day, because she was getting sick often and needed a feeding tube inserted in her stomach.

“From the ages of 1 to 5, she spent 65 percent of her life in the hospital,” her mom, Melanie, said. “It takes her 10 hours a day just to eat. She’s medically fragile.”

According to Walker, development and aging are at opposite poles of the life continuum, but they are controlled by the same genes. In young childhood, these genes initiate structure and function and coordinate change (single cells eventually become full-functioning adults).

“Once we’re adults, we don’t want to change,” Walker said. “We all want our bodies to be about 21. But those genes don’t turn off at that time. It causes the bodies’ stability to erode, and that’s what aging is. The punchline: if you can get those genes and turn them off, then you wouldn’t have aging.”

Essentially, Brooke’s aging and development genes have been turned off.

Her bones are that of a 10-year-old, her teeth are 6-years-old, her brain is less than a year old, Walker said.

Yet, her hair and nails, protein synthesis, grow normally.

“We’re still searching for the mutation,” Walker said. “Once we find it, we are going to try to manipulate it in experimental animals to see if we can extend their lifespan.”

In the meantime, the Greenberg family takes each day with Brooke as it comes. They don’t dwell on the negative; instead, they consider Brooke’s life a gift.

“Maybe she holds the keys to medical history,” Caitlin said.

To learn more about Brooke’s story, watch Child Frozen in Time Sunday at 9 p.m. on TLC.